In general, a hydraulic excavator which is a typical example of a construction machine is largely constituted by a lower traveling structure, an upper revolving structure rotatably mounted on the lower traveling structure, and a working mechanism provided capable of moving upward/downward on the front side of the upper revolving structure.
The upper revolving structure is largely constituted by a revolving frame, an operator's seat provided on the revolving frame and on which an operator is seated, an engine located on the rear side of the operator's seat and mounted on the revolving frame, a hydraulic pump provided on the engine, an operating oil tank located on the right side of the operator's seat and provided on the revolving frame and storing an operating oil to be supplied to the hydraulic pump, and a fuel tank provided on the revolving frame and storing a fuel to be supplied to the engine.
Here, as a hydraulic excavator suitably used for an excavating work of a gutter and the like, a swing-type hydraulic excavator having a working mechanism swingably in the left-right direction with respect to the upper revolving structure can be cited. In this swing-type hydraulic excavator, a swing post located on the front side of the revolving frame constituting the upper revolving structure and made to swing in the left-right direction by a swing cylinder is provided, and the working mechanism is mounted on the swing post, capable of moving upward/downward (Patent Document 1).
In such swing-type hydraulic excavators, the operating oil tank and the fuel tank are arranged above the swing cylinder adjacently in the front-rear direction in order to effectively use an installation space for equipments in the upper revolving structure. Thus, in a conventional art, such a hydraulic excavator is known that, when a maintenance work for the swing cylinder is to be performed and the like, the fuel tank is constructed to be fixed to the revolving frame by using a fixing belt in order to mount/remove the fuel tank to/from the revolving frame easily (Patent Document 2, Patent Document 3).
On the other hand, as another conventional art, a structure for fixing the fuel tank by arranging two fixing belts on an outer peripheral surface of the fuel tank in a vertical direction or in the left-right direction in parallel is proposed (Patent Document 4, Patent Document 5). Moreover, a structure for fixing the fuel tank by crossing two fixing belts with each other in a cross-state on the outer peripheral surface of the fuel tank is proposed (Patent Document 6).